This product was extremely easy to install in a dryer vent. It stopped the backdraft coming in from outside in one of the coldest winters this area saw in 20 yrs. I would recommend this product to anyone looking for a solution to stopping a backdraft in a 4" dryer vent.

I would have hoped that the unit would have blocked more of the cold air from coming in: the hinge is not air sealed. Installing two in one duct blocked a satisfactory amount of the air--although at the cost of creating more resistance for the fan to blow against. Since I have variable speed fans that will always try to blow their rated CFM, I wasn't too concerned about this. On the plus side: they are easy to install in a retro-fit situation: no need to tear open walls, just pull the fan and insert into the duct.

We live in Iowa where the winter wind can be cold and hard. Last year we moved into a new build home and experienced the kitchen exhaust hood as well as the bathroom fan vents allowing a lot of cold air to enter the house. My wife complained a great deal as she was home during the day and the house was cold all the time. I searched on-line for a solution and discover the 4 and 6 inch dampers, and finally ordered them this fall. Thought I would have needed a professional to install them, but to my surprise I was able to do this project in under one hour (4 units). The dampers are simple and affective. Yes we had not yet seen the Iowa winter, but we have noticed a change in amount of outside noise is not in the house any more. Perfect solution, at a low price! No Brainer!

Works great. We bought about 4 different types/brands of these. The others didn't work well, had parts coming off the pipe that interfered with connection. This by far the best of the butterfly dampers I saw.

I had to take the spring out and turn it around and add another twist. After that it worked great and I could notice the difference right away in the bathroom that always had a breeze in it from the exhaust fan.

I bought fantech inline fans but opted for the Aldes inline dampers for an extra buck or two. And am I glad I did. These are really cool, work flawlessly, and fit seemlessly into my 4 inch duct lines in a dual inline bath fan application keeping backdrafts a thing of the past. These have a foam collar that fits snugly into the ductline and form a tight seal. A well-engineered butterlfy valve and spring open while exhausting shower steam and after dinner methane while shutting out mother nature. Would buy again, and would advise you to do the same.

I used this for a FanTech installation on a bathroom. At first, I thought it was rather expensive. After installation, I thought about the cost of years of cold air infiltrating my bathroom, and came to the conclusion that it is a very inexpensive solution to a persistant problem--it works like a champ!